Judge Mr Justice MacDuff lifted a reporting restriction to reveal Williams was the former partner of Rebecca Shuttleworth, 25, who was found guilty in June of murdering her two-year-old son, Keanu Williams, in a totally separate case.

Jailing Williams for a minimum of 29 years at Birmingham Crown Court, the judge described the cannabis user as being “clearly evil and dangerous beyond measure.”

The judge said: “She wanted no further part of a relationship with you and you decided to kill her, in fact, to execute her.

“It was your decision, casually taken. She had to die. And then you killed Harrison, probably as he lay asleep in his cot. The casual way in which you committed these killings was chilling.

“Your subsequent behaviour demonstrated how unconcerned you were at what you had done. You behaved in a totally relaxed way as though this was a mere trifle. You are clearly evil and dangerous beyond measure.”

Peter Grieves-Smith, prosecuting, said Williams had previously been jailed for savagely attacking his sister’s ex-partner in an attack involving a hammer and samurai swords.

He carried out the killings of Yvonne and Harrison just four months after his release from prison for that offence.

Williams formed a relationship with Ms Walsh, a graduate in social care, but shortly before her death she had ended it.

Mr Grieves-Smith said: “He could not accept her rejection. Quite why he chose to kill Harrison, a child he had looked after and appeared to care for, is unknown.”

He said Ms Walsh, who worked as a mental health worker at the Oakview centre in Moseley
, was found in her bedroom with the duvet pulled up. She had no defensive injuries and would have been caught totally off-guard.

Both she and Harrison, who was found in his cot, had ligature marks around their necks.

Rajiv Menon QC, defending, said there had never been any dispute that he killed Ms Walsh and her son.

The judge said he had read “harrowing” statements from friends and relatives of Ms Walsh. He added that the agony the mum must have gone through in her final conscious minutes was “almost unimaginable.”

Speaking outside court Yvonne’s brother Chris Walsh said: “Words cannot describe how we feel. We usually all spend time together over Christmas but now we can’t. Yvonne and Harrison won’t be there and it is such a loss for us.

“Yvonne was so joyful, she was the centre of attention because she was always so happy and such a doting mum.

“We are struggling as a family to come to terms with all of this. We are all there for each other but it is so difficult and emotional.’’

Detective Chief Inspector Sarbjit Johal, from the homicide investigation team at West Midlands Police, said: “Wesley Williams has today been sentenced to a lengthy stay in prison for the shocking and senseless murders of his partner Yvonne and her baby Harrison - who both had their whole lives ahead of them.

“Yvonne’s family described her as a warm and loving person who was a dedicated professional and absolutely devoted to her two young children.

“My thoughts are with their family, friends and the community that they lived in who are all still struggling to come to terms with their deaths.”